This document specifies a gravimetric method for the determination of rare earth content in 11 kinds of individual rare earth metals (lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium and yttrium) and their compounds, such as oxides, carbonates, hydroxides, oxalates, chlorides and fluorides.

The determination ranges for the rare earth content in mass fraction are as follows:

—     rare earth metal: 98,0 % (mass fraction) to 99,5 % (mass fraction);

—     rare earth oxide: 95,0 % (mass fraction) to 99,8 % (mass fraction);

—     rare earth oxalate: 95,0 % (mass fraction) to 99,8 % (mass fraction);

—     rare earth fluoride: 75,0 % (mass fraction) to 90,0 % (mass fraction);

—     other compounds (i.e. rare earth hydroxide, rare earth chloride and rare earth carbonate): 40,0 % (mass fraction) to 70,0 % (mass fraction).

It does not apply to individual rare earth metals and their compounds when:

a)       the matrixes of the sample are erbium, thulium, ytterbium and lutetium;

b)       the content of thorium or lead in the sample is greater than 0,1 % in mass fraction.